An explosive material is a material that contains a great amount of potential energy and which can produce an explosion if the energy is released suddenly, usually accompanied by the production of light, heat, sound, and/or pressure. Examples of explosive compounds include ammonium nitrate, nitroglycerin, acetone peroxide, trinitrotoluene (TNT), nitrocellulose, RDX, PETN, and HMX. Recently, the detection of explosives in venues such as ports, airports and other border entries has become important in view of the risk of terrorist attacks.
The detection of explosive compound residues has been attempted with a number of different technologies, including mass spectroscopy, fluorescence detection, and nitric oxide detection. Mass spectroscopy requires expensive and cumbersome equipment that needs frequent maintenance. Fluorescence detection may not be sensitive enough for all applications, and requires that samples be accessible to sampling by wipes that are then irradiated to detect any residue. Nitrogen monoxide detection has been developed based on the principle that many explosives can be made to generate nitrogen monoxides. Conventional equipment used in these techniques is relatively insensitive, requires frequent calibration and service, and may not detect explosives.